In general, the present invention relates to a display control apparatus, a display control method and a presentation medium. More particularly, the present invention relates to a display control apparatus, a display control method and a presentation medium which are capable of changing the point of sight of a user to a proper position dynamically in an operation to display a 3-dimensional virtual space.
In the field of so-called personal-computer communication services wherein a plurality of users each connect its own personal computer to a central host computer through a modem provided for the personal computer and a public telephone line network to make an access to the host computer in accordance with a predetermined communication protocol as is the case with NIFTY-Serve (a trademark) of Japan and CompuServe (a trademark) of the US, a cyberspace service known as Habitat (a trademark) is known.
The development of Habitat was started in the year of 1985 by a US company named LucasFilm. After Habitat was operated by QuantumLink, a US company rendering services through commercial networks, for about 3 years, Fujitsu Habitat (a trademark) was started in February 1990 to render services of NIFTY-Serve. In Habitat, a place and status of each user, that is, an object representing the status and place of the user, are sent to a virtual city called a populopolis, a 2-dimensional graphical drawing, allowing the users to have chats among them. The object is referred to as an avatar which means an incarnation of an Indian deity told in an Indian myth. In actuality, a Habitat chat is a real-time conversation based on texts entered and displayed in terms of characters. For more detailed explanation of Habitat, refer to a reference with a title of "Cyberspace" authored by Michael Benedikt, an NTT publication ISBN4-87188-265-9C0010 with a first edition published on Mar. 20, 1994 or "Cyberspace: First Steps" authored by Michael Benedikt, a 1991 edition, published by MIT Press Cambridge, Mass. ISBNO-262-02327-X, pages 282 to 307.
In a conventional cyberspace system implemented by personal-computer communication services of this type, a scene of a row of virtual houses on a virtual street and the interior of a virtual room are drawn as 2-dimensional graphics. The avatar is merely moved up and down on a background of a 2-dimensional graphic in order to move to an inner or outer position with respect to the viewer in a virtual space. Thus, to realize a pseudo experience of a walk or a behavior in a virtual space, the power of expression on the display of the virtual space is considered to be weak. In addition, a virtual space in which the avatar representing the status and the place of the user itself and the avatar of a partner are displayed is seen at a point of vision of a third party. Also at this point, a sense of a pseudo experience is lost.
In order to solve this problem, a virtual space is displayed as a 3-dimensional graphic as is disclosed in Japanese Patent Laid-open No. Hei9-81781. In this solution to the problem, a function allowing the user to walk through the point of vision of an avatar is implemented by utilizing a VRML (Virtual Reality Modeling Language), a descriptive language for describing 3-dimensional graphical data. A consideration of a variety of cyberspaces, which are used for letting avatars each representing a user have chats, is described in Nikkei Electronics, Sep. 9, 1996, No. 670, pages 151 to 159.
When walking through a 3-dimensional virtual space, that is, a virtual space displayed as a 3-dimensional graphic as described above, at the point of vision of an avatar, the user is capable of feeling a sense as if the user were indeed present in the 3-dimensional virtual space.
In a 3-dimensional virtual space, by the way, an event that exists in reality and, of course, a hypothetical event fancied by a human being can be implemented. A hypothetical event fancied by a human being is, for example, a state in which the soul of the human being departs from the body, becoming another human being observing a fanciful world wherein the other human being itself exists. To put it concretely, assume for example that the point of vision of the user is made a point of vision at which an avatar representing the user itself is visible. A n avatar representing the user itself is appropriately referred to hereafter as a pilot avatar. At such a point of vision, the user is capable of seeing the pilot avatar which represents the user itself. In this case, the user turning into a soul observes the pilot avatar representing the user itself who really exists. That is to say, the user is capable of feeling a sense as if the user had departed from its own body as a soul.
By merely making the point of vision of the user an arbitrary point of vision at which the pilot avatar is visible, that is, by merely presenting a picture of a 3-dimensional space including the pilot avatar, however, the sense of a pseudo experience may be lost in some cases.
If the direct front of the face of the pilot avatar is used as a point of vision of the user for example, the closed-up face of the pilot avatar is displayed so that it is difficult for the user to feel a sense as if the user turning into a soul were observing the user itself who really exists.
With an arbitrary point of vision, at which the pilot avatar is visible, used as a point of vision of the user as it is, it is possible to provide a sense felt as if the user had departed from the body as a soul. In this case, however, a virtual space in which the pilot avatar and the avatar of a partner are displayed is seen at a point of vision of a third party. It is thus difficult for the user to feel a sense as if the user itself were present in a virtual world, that is, to feel a sense as if the user itself were present in a virtual world, walking about through the virtual world. It should be noted that the avatar of a partner is appropriately referred to hereafter as a drawn avatar.
For this reason, convenience will be obtained if it is possible to switch from a state of making the point of vision of the user coincident with the point of vision of the pilot avatar to a state of not making the point of vision of the user coincident with the point of vision of the pilot avatar and vice versa.
In the case of a state in which the point of vision of the user is not made coincident with the point of vision of the pilot avatar, it is desirable to place the point of vision of the user at a point at which the user is capable of feeling a sense as if the user turning into a soul were observing the user itself who really exists. To put it concretely, if the user is capable of seeing scenery being seen by the pilot avatar representing the user itself along with the pilot avatar, the user is expected to be capable of feeling a sense as if the user turning into a soul were observing the user itself who really exists. It is desirable to present such a picture right after establishing a state in which the point of vision of the user is made not coincident with the point of vision of the pilot avatar.